Saturday, September 22, 2007

Evolution of the Whale Ear

"The ‘whale’ status of Pakicetus received another potentially fatal blow. This came from a recent study of the semicircular canal systems in both living and fossil cetaceans (whales and dolphins).1 The semicircular canal system is a set of tubes connected to the inner ear that provides information on head (and therefore also body) movements. The tubes are filled with small, solid particles suspended in liquid. The inner surfaces of the tubes are covered with sensors that show which way the contents are flowing. This organ gives us our sense of balance.

To the surprise of the international team of scientists, the cetaceans, both living and fossil, all had the same ‘unique’ small canal size—about three times smaller than all other mammals, when corrected for body size.1 The researchers suggested that the canal system had to be small to reduce the sensitivity, thus preventing information overload as the animals rolled around.1 They concluded that the early whales had semicircular canals unlike those of any non-cetacean mammal. This, they said, shows that even the ‘earliest’ whales had unique behaviour, suited to aquatic life.

But while the paper defended whale evolution, the detailed analysis demonstrated a sharp gap in relative sizes between whales and non-whales, including the pakicetid Ichthyolestes (creationists would probably group it into the same created kind as Pakicetus). There were no examples of slow and gradual shrinking of the canals—they were either one relative size or the other.2 In fact, the paper affirms that the alleged change in canal structure happened ‘instantaneously’ and produced a ‘unique’ apparatus."

So the shrinking of the semicircular canals happened "instantaneously"; and it of course follows from this that evolution is wrong. Right? Uh-Uh. You see, the fact that the evolution of the canals happened rapidly while the evolution of the rest of the body happened more slowly is not evidence against evolution. These canals are used for maintaining balance. Movement in the water, and balance in the water, would be very different from movement and balance on land. These canals would be a very important step in evolution, and therefore this adaption would spread much quicker than other adaptions might. The Science Blog Afarensis has a good article on this.

The same type of claims about semicircular canals have been made before, except with Apes and humans instead of whales. The man that AiG references, Fred Spoor, has admitted that "Any link between the characteristic dimensions of the human canals and locomotion will be more complex than a simple association with the broad categories of quadrupedal vs. bipedal behavior." So the inner ears are just not enough to draw any simple conclusions from.

"The skulls of pakicetids have an ear region that is highly unusual in shape, and only resembles that of modern and fossil whales. These features are diagnostic for cetaceans, they are found in all cetaceans, and in no other animals. These features are main why pakicetids are considered whales. In many other features, pakicetids are also similar to some whales, but those features are not shared by all whales. An example of the latter is the dentition. Pakiceid teeth look a lot like those of fossil whales, but are unlike those of modern whales. Pakicetids did not live in the sea. The rocks in which their fossils are preserved indicate that the bones were buried in a shallow stream, and that the climate was hot and dry. It is likely that pakicetids waded in these streams. Their bones are unusually thick, possibly an adaptation to make the animal heavier counteracting the buoyancy of the water."

So there are many indications that they are ancestors of whales, and that they were semi aquatic.

It's sad that AiG does absolutely no research to back up their claims. They make blind and bold assertions that simply have no basis in science. This is such a very clear cut case of evolution, too. Pakicetus was found in the early Eocene strata, Ambulocetus was found in the early to middle Eocene, and Rodhocetus was found in the mid to late Eocene. It's very sequential.

Having visited AiG a couple of times I possibly agree with you about the lack research, however I can see similar issues with your AiGBusted site. You seem to rely upon single papers, some of which I have checked on are not strictly correct. For instance the article that states that larger shale particles would sink through the finer sand would be correct is they were in a perfectly still environment, any vibrationary influences would cause the fine particles to fall through the spaces between the coarse shale. Once each particle reaches the base of sand it joins very quickly into the tessellated foundation eventually leaving the coarse shale on top. You can test this out for yourself if you like in a fish tank, lay the layers into the water and apply some vibration, either mechanically or through water movement.

So sorry I don't think much of either site. If I had the time I could possibly come up with explanations for everything you slam AiG for. Please do your homework, don't rely on the opinion of just one so called expert, a good scientist tests everything as many times as is practical. Have an open mind, not one that is consumed by proving someone wrong (or right) then the scientific community may take you seriously.